This project will concentrate on the characterization of unbroken chromosomal DNA from bacteria and higher organisms. Studies on bacterial chromosomes will be emphasized initially. After lysis of the cells and disruption of the nuclear structure, the DNA will be characterized by physico-chemical methods which recent developments have made available for work on the giant molecules expected. These methods include sedimentation in a gradient at low speed to avoid a sedimentation anomaly otherwise encountered with large DNA, and the use of a new instrument to measure both the viscosity and the viscoelastic recoil of dilute DNA solutions. These measurements can be carried out on impure lysis mixture, but a search will also be made for methods of purifying the DNA without breaking the exceedingly fragile molecules. Studies on the techniques and theory of the methods themselves will also be undertaken. Studies will also be carried on the size of the single strands of DNA (alkaline DNA) isolated from bacteria and from higher organisms.